#!/usr/bin/python
#
# Copyright (C) 2008 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


__author__ = 'api.jscudder (Jeff Scudder)'


import urlparse
import urllib


DEFAULT_PROTOCOL = 'http'
DEFAULT_PORT = 80


def parse_url(url_string):
    """Creates a Url object which corresponds to the URL string.

    This method can accept partial URLs, but it will leave missing
    members of the Url unset.
    """
    parts = urlparse.urlparse(url_string)
    url = Url()
    if parts[0]:
        url.protocol = parts[0]
    if parts[1]:
        host_parts = parts[1].split(':')
        if host_parts[0]:
            url.host = host_parts[0]
        if len(host_parts) > 1:
            url.port = host_parts[1]
    if parts[2]:
        url.path = parts[2]
    if parts[4]:
        param_pairs = parts[4].split('&')
        for pair in param_pairs:
            pair_parts = pair.split('=')
            if len(pair_parts) > 1:
                url.params[urllib.unquote_plus(pair_parts[0])] = (
                    urllib.unquote_plus(pair_parts[1]))
            elif len(pair_parts) == 1:
                url.params[urllib.unquote_plus(pair_parts[0])] = None
    return url

class Url(object):
    """Represents a URL and implements comparison logic.

    URL strings which are not identical can still be equivalent, so this object
    provides a better interface for comparing and manipulating URLs than
    strings. URL parameters are represented as a dictionary of strings, and
    defaults are used for the protocol (http) and port (80) if not provided.
    """
    def __init__(self, protocol=None, host=None, port=None, path=None,
                 params=None):
        self.protocol = protocol
        self.host = host
        self.port = port
        self.path = path
        self.params = params or {}

    def to_string(self):
        url_parts = ['', '', '', '', '', '']
        if self.protocol:
            url_parts[0] = self.protocol
        if self.host:
            if self.port:
                url_parts[1] = ':'.join((self.host, str(self.port)))
            else:
                url_parts[1] = self.host
        if self.path:
            url_parts[2] = self.path
        if self.params:
            url_parts[4] = self.get_param_string()
        return urlparse.urlunparse(url_parts)

    def get_param_string(self):
        param_pairs = []
        for key, value in self.params.iteritems():
            param_pairs.append('='.join((urllib.quote_plus(key),
                urllib.quote_plus(str(value)))))
        return '&'.join(param_pairs)

    def get_request_uri(self):
        """Returns the path with the parameters escaped and appended."""
        param_string = self.get_param_string()
        if param_string:
            return '?'.join([self.path, param_string])
        else:
            return self.path

    def __cmp__(self, other):
        if not isinstance(other, Url):
            return cmp(self.to_string(), str(other))
        difference = 0
        # Compare the protocol
        if self.protocol and other.protocol:
            difference = cmp(self.protocol, other.protocol)
        elif self.protocol and not other.protocol:
            difference = cmp(self.protocol, DEFAULT_PROTOCOL)
        elif not self.protocol and other.protocol:
            difference = cmp(DEFAULT_PROTOCOL, other.protocol)
        if difference != 0:
            return difference
        # Compare the host
        difference = cmp(self.host, other.host)
        if difference != 0:
            return difference
        # Compare the port
        if self.port and other.port:
            difference = cmp(self.port, other.port)
        elif self.port and not other.port:
            difference = cmp(self.port, DEFAULT_PORT)
        elif not self.port and other.port:
            difference = cmp(DEFAULT_PORT, other.port)
        if difference != 0:
            return difference
        # Compare the path
        difference = cmp(self.path, other.path)
        if difference != 0:
            return difference
        # Compare the parameters
        return cmp(self.params, other.params)

    def __str__(self):
        return self.to_string()
